gen_makefile.py: drop argument for deps file

Rename 3G+2G.deps to all.deps and remove the parameter from
gen_makefile.py. Create new Makefile targets for the various use cases,
usually we build either 'cn-bsc' or 'usrp'. The next patch will add more
projects to all.deps.

This change brings the Makefile logic closer to how it is actually used,
one build directory that is building most Osmocom projects. New projects
can be added to all.deps on demand, but then we have it in the
repository and not just a local change that we add temporarily to the
3G+2G.deps file when we need to build a specific project.

Extend all.deps with projects needed by ttcn3.sh, so it doesn't need to
write its custom .deps file anymore.

Change-Id: I6394882f67eecda3d2c03a97d3119657f7d3873f
5 files changed